Zn-Catalyzed Sustainable One-Pot Synthesis of Rubber Accelerator TMTM and Lubricant Additive TPPT

A greatly improved process for simultaneously producing the widely applied rubber accelerator tetramethylthiuram monosulfide (TMTM) and lubricant additive triphenyl thiophosphate (TPPT) from inexpensive and nontoxic feedstock tetramethylthiuram disulfide (TMTD) and triphenylphosphite (TPPi) is herein reported. Zinc oxide is used as an efficient and readily recyclable heterogeneous catalyst. The biomass-derived γ-valerolactone (GVL) is employed as a green solvent. The new process proceeds smoothly under mild conditions, with excellent yields of TMTM and TPPT (62 and 78% in a small scale and 68 and 49% in a large scale). The mechanism of this transformation was elucidated by X-ray diffraction (XRD), in situ IR, and high-resolution mass spectrum (HRMS) analyses. A feasible strategy of separating the two high-value-added products by filtration and recrystallization has been established as well.